The microSHIFT Acolyte RD‑M5185M‑B Rear Derailleur is a robust, trail‑ready 1×8‑speed derailleur engineered for riders who want wide‑range gearing, simple setup, and reliable chain control. Built around microSHIFT’s innovative SpringLock chain‑retention system, this derailleur keeps the chain secure over rough terrain while maintaining smooth, responsive shifting.

The SpringLock mechanism uses a customized high‑tension spring and a dual‑stage activation system. When engaged, it provides exceptional chain stability; when disengaged, wheel removal becomes quick and easy. To activate the clutch, simply turn the engagement bolt clockwise until it clicks. To disengage, flip the switch—no tools required.

Designed specifically for the Acolyte 1×8 ecosystem, the RD‑M5185M‑B works with wide‑range 12–42T and 12–46T cassettes and Acolyte shifters only, making it an ideal upgrade for trail bikes, youth MTBs, and riders seeking simplicity without sacrificing performance.

• Speed: 1×8‑speed


• Cage Length: Medium


• Chain Retention: SpringLock clutch system


• Max Cassette Range: 12–42T and 12–46T compatible


• Capacity: 37T


• Shifter Compatibility: Acolyte shifters only


• Cable Routing: Direct‑path for smooth, responsive shifting


• Ideal for MTB, trail, and youth performance bikes

The RD‑M5185M‑B delivers the simplicity of an 8‑speed drivetrain with the chain security and performance normally found on higher‑end systems—perfect for riders who want durability, control, and value.